Still Linux falls off DMZ

Well ... our problem has returned ... we were fine for many weeks, but
alas it returned ... see my first posting for all of our attempts.
(http://groups.google.com/groups?hl=e...rev=/&frame=on)

Rik asked about disappearing:
After an undetermined amount of time the RH Linux 7.3 box just falls
off the network and becomes invisible to the rest of the world. If I
am actually LOGGED into the box at the time, I can still do anything
from that box without problem. Plus I can ping the pix firewall, check
routing, etc. ... but until I do something that is inbound network
related (like ssh from a nearby server in the DMZ to this box),
nothing will restart.

Upon an ssh from a nearby box (even with no password), EVERYTHING
comes right back up. We have tried a consistant ping from another
machine ... but that is just a workaround, not an answer.

Once the machine "falls off" nothing except local DMZ boxes can ping
or ssh to it.

Mark: we are going to try your suggestion again ... it didn't work
last time though.

Any additional thoughts???